Stator for an electric machine, in particular for an electric drive machine of an electric or hybrid vehicle

Abstract

The invention relates to a stator for an electric machine, in particular for an electric drive machine of an electric or hybrid vehicle, comprising a number of stator teeth (21) projecting from a stator yoke (19), wherein a stator groove (23) is formed between each pair of stator teeth (21), into which a stator winding (13) is inserted.In a stator designed simply for adequate cooling, the free ends of the stator teeth (21) are free of projections towards the stator slot, and the stator slots (23) are covered by a separate closure structure (17) consisting of a first thermally conductive component (25) which has two tangential projections per stator slot (23) designed as tooth feet (27) projecting into the stator slot, and a second thermally conductive and poorly electrically conductive component (29) which closes a gap between the respective tooth feet (27) opposite each other in each stator slot (23).

Description

[0001] The invention relates to a stator for an electric machine, in particular for an electric drive machine of an electric or hybrid vehicle, comprising a number of stator teeth projecting from a stator yoke, wherein a stator groove is formed between each pair of stator teeth, into which a stator winding is inserted.

[0002] From DE 10 2017 211 317 A1, a stator of an electric machine is known, which has a stator lamination stack with a stator yoke on which a number of radially oriented stator teeth extend. Between the stator teeth, a corresponding number of stator slots are formed for receiving a stator winding. The free ends of the stator teeth have axially aligned stator feet, between which and the stator winding an axially extending cooling channel is positioned.

[0003] The object of the invention is to provide a stator for an electric machine which is simply designed for sufficient cooling.

[0004] The invention is defined by the features of the independent claims. Advantageous further developments and embodiments are the subject of the dependent claims. Further features, applications, and advantages of the invention will become apparent from the following description and the explanation of exemplary embodiments of the invention illustrated in the figures.

[0005] The problem is solved by the subject matter of claim 1.

[0006] In the stator described above for an electric machine, in particular for an electric drive machine of an electric or hybrid vehicle, comprising a number of stator teeth projecting from a stator yoke, wherein a stator groove is formed between each pair of stator teeth in which a stator winding is inserted, the free ends of the stator teeth are free of a projection in the direction of the stator groove, wherein the stator grooves are covered by a separate closure structure, which consists of a first highly thermally conductive component, which has tangential projections in the stator groove formed as tooth feet, and a second highly thermally conductive and poorly electrically conductive component, which closes a gap between the respective tooth feet opposite each other in each stator groove.By eliminating the stator feet attached to the free ends of the stator teeth, any type of stator winding can be inserted radially into the stator slots from below, thus reducing assembly effort. The separate locking structure, with its first component, takes over the function of the stator tooth feet due to its magnetic conductivity, thereby reducing the torque ripple of the rotating magnetic field generated by the electric machine. Simultaneously, the locking structure's second component, which is highly thermally conductive but poorly electrically conductive, allows heat generated by the stator winding to be dissipated from the stator slot to the axial ends of the active length of the electric machine. The active length is defined by the components of the electric machine that actively participate in the electromagnetic field, such as the stator and rotor laminations, windings, and magnets.

[0007] Advantageously, the second component of the separate locking structure, which is highly thermally conductive but poorly electrically conductive, wedges into the gap between the opposing tooth bases of the first component, which is highly thermally conductive. This creates a permanent and reliable connection between the two components of the locking structure, which can be positioned on the stator as a prefabricated component.

[0008] In one embodiment, the separate locking structure is positively locked and / or force-locked and / or material-locked to at least one stator tooth. The fastening of the locking structure to the stator can thus be carried out in a single process step.

[0009] In one variant, the separate sealing structure extends beyond the active length of the electric machine to participate in active cooling of the electric machine on both sides. By integrating the sealing structure into the existing cooling system within the electric machine, additional cooling measures in the stator slots are eliminated, thus reducing manufacturing costs.

[0010] In one embodiment, the separate locking structure is ring-shaped. This ring-shaped design allows for advantageous adaptation to the dimensions of the stator and further simplifies the assembly process. It is particularly advantageous if the ring-shaped locking structure is designed in one or two parts for axial insertion into the stator from one or both sides.

[0011] In a further embodiment, each stator winding inserted in a stator slot is at least partially surrounded by insulating paper. The insulating paper serves to prevent direct electrical contact between the stator winding and the stator, thus reducing the risk of short circuits.

[0012] In another variant, the area of ​​the stator winding opposite the second component of the locking structure, which has good thermal conductivity but poor electrical conductivity, is free of insulating paper. This improves heat dissipation from the stator winding to the locking structure.

[0013] In another embodiment, the spaces between the stator winding and stator teeth, as well as the locking structure, in each stator slot are filled with an impregnating agent. This impregnating agent not only increases the mechanical fixation of the locking element to the stator, but also improves heat dissipation from the stator slot through direct contact with the second component, which is highly thermally conductive and poorly electrically conductive.

[0014] It is advantageous to use a wave winding as the stator winding, inserted into the stator slot. Such wave windings represent a variant of stator windings where welding is not required on one side, as they are inserted into the stator slot from below. For this, the stator laminations must be modified by removing the stator tooth root to accommodate the stator winding or the current conductor.

[0015] Further advantages, features, and details will become apparent from the following description, in which—possibly with reference to the drawing—at least one exemplary embodiment is described in detail. Features described and / or illustrated can, individually or in any meaningful combination, constitute the subject matter of the invention, possibly also independently of the claims, and can, in particular, also be the subject of one or more separate applications. Identical, similar, and / or functionally equivalent parts are designated with the same reference numerals.

[0016] They show: Fig. 1 an embodiment of an electric machine with the stator according to the invention, Fig. 2 a section through the stator according to the invention in the area of ​​the active length of the electric machine, Fig. 3 a first embodiment of the stator according to the invention, Fig. 4 a further embodiment of the stator according to the invention, Fig. 5 a section through the stator according to the invention in the area outside the active length of the electric machine, Fig. 6 a top view of a closure structure for the stator slots, Fig. 7 a perspective view for mounting the locking structure on the stator, Fig. 8 Several embodiments for the active cooling of the electric machine comprising the stator according to the invention.

[0017] In Fig. Figure 1 shows an embodiment of an electric machine with the stator according to the invention. The electric machine 1 is intended in particular for use in electrically powered vehicles. The electric machine 1 comprises a rotor 5 rotatably mounted on a rotor shaft 3, the rotor shaft 3 being guided in rotor bearings 7 arranged on a housing 9 of the electric machine 1. A stator 11 surrounds the rotor 5 within the housing 9. The stator 11 is fixed to the housing 9. Stator windings 13 are arranged within the stator 11, the winding heads 15 of which project axially beyond the stator 11 on both sides. The stator 11, the rotor 5, the stator windings 13 ( Fig. Magnets (3 or 4), not shown further, and other components that influence the electromagnetics of the electric machine are called active parts. Their axial extension is referred to as the active length AL.

[0018] All other components are described as passive components.

[0019] A closure structure 17 extends along the longitudinal extent within the stator 11 and is, for example, ring-shaped. A section through the stator 11 according to the invention with the closure structure 17 in the region of the active length of the electric machine 1 is shown in Fig. 2 shown. Fig. Figure 2a shows a cross-section of the stator 11 and Fig. 2b an enlarged stator section. The stator 11 consists of a stator yoke 19, on which a plurality of stator teeth 21 are arranged, oriented radially inwards towards the rotor 5. Between each pair of stator teeth 21, a stator groove 23 is formed, which is closed off by the annular closure structure 17 ( Fig. 2a).

[0020] The closure structure 17 comprises, as shown in Fig. Figure 2b illustrates a first interrupted ring-shaped component 25, which has stator tooth feet 27, two of which are tangentially opposite each other in each stator slot 23 and contribute to reducing the torque ripple of the rotating magnetic field generated by the rotor 5. The first component 25 can, for example, be made of the same material as the stator lamination and be designed as electrical steel. However, it can also be made of a metal, a grain-oriented or non-grain-oriented material, or a magnetically conductive material.

[0021] A second annular component 29 of the closure structure 17 has wedge-shaped projections 31, each wedge-shaped projection 31 engaging from the direction of the stator groove 23 into the space between the two stator tooth bases 27 of the first component 25. The second interrupted annular component 29 consists of a material with good thermal conductivity but poor electrical conductivity, such as a polymer. A thermoset polymer, such as a multi-component resin like epoxy resin, can be used, which may be filled with particles, fibers, or powder to improve thermal conductivity. Materials such as silicon dioxide, aluminum oxide, aluminum nitride, boron nitride, or silicon nitride can be added to the second component 29. The thermal conductivity is, for example, greater than 3 W / (m*K).

[0022] The locking structure 17, assembled from the first component 25 and the second component 29, closes the stator slots 23 after a winding, e.g., a shaft winding 33 radially from below, has been inserted into each stator slot 23. The locking structure 17 is pressed against the stator teeth 21 or connected by force or form fit. For this purpose, each stator tooth 21 has a receptacle 35 with an undercut at its end facing the rotor 5, into which a pressing element 37 formed on the locking structure 17 engages in a form-fit manner.

[0023] Two different embodiments of the stator 11 according to the invention are shown in Fig. 3 and Fig. Figure 4 shows the stator slots 23 each filled with a wave winding 33. Before the wave windings 33 are inserted into the stator slot 23, an insulating paper 39 is placed in the slot as a lining, which then completely encloses the wave winding 33 ( Fig. 3) After attaching the closure structure 17, the cavities remaining in the stator grooves 23 are filled with an impregnating agent 41 in the form of, for example, a potting compound.

[0024] As in Fig. As shown in Figure 4, the insulating paper 39 can be dimensioned such that it is missing on the side facing the second component 29 of the closure structure 17, which improves heat dissipation.

[0025] A section through the stator 11 according to the invention in the area outside the active length AL of the electric machine 1 is shown in Fig. Figure 5 shows only the end ring 43 formed by the second component 29 of the closure structure 17. The end ring 43 can be made of the same material as the second component 29 of the closure structure 17 and thus also exhibit good thermal conductivity.

[0026] Fig. Figure 6 shows a top view of a closure structure 17 for the stator slots 23, which is formed in two parts in the axial direction, with each half-part 45, 47 corresponding to half the length of the active components of the electric machine plus the width of the end ring 43. The two half-parts 45, 47 are inserted into the stator 11 from both sides ( Fig. 7) Alternatively, it is also possible to insert the entire closure structure 17 into the stator 11, wherein the closure structure 17 has twice the length of the half parts 45 and 47.

[0027] Several embodiments for the active cooling of the electric machine comprising the stator according to the invention are described in Fig. 8 shown. Fig. 8a The rotor shaft 3 is hollow to introduce a coolant 49, such as oil, airflow, or a dielectric fluid, into the electric machine 1 from the outside. Due to centrifugal force, the coolant 49 is injected through radial channels 51 in the rotor shaft 3 into the interior of the housing 9, where it cools the winding heads 15 protruding from the stator 11. Since the end ring 43 of the closure structure 17 extends beyond the active length AL of the stator 11, it comes into contact with any type of coolant 49, which further promotes heat dissipation from the stator 11.

[0028] Alternatively, direct convective cooling of the ring ends 43 of the closure structure 17 can be achieved by directing the coolant 49, preferably oil, radially to the winding heads 15 ( Fig. 8b). Since the end ring 43 is located below the winding heads 15, the coolant 49 drips radially within the housing 9 from the winding head 15 onto the end ring 43. In addition, a further quantity 53 of the coolant 49 can be introduced into the space between the stator windings 13 and thus come into direct contact with the end ring 43.

[0029] In Fig. Figure 8c shows another method of active cooling. The coolant 49 is supplied from the outside to the winding head 15 and thus to the end ring 43 via a coolant supply line 55 or a coolant supply opening 57 formed in the housing 9.

[0030] In Fig. In section 8d, the end ring 43 forms a partition between the stator and rotor chambers with the housing 9, whereby the stator 11 is partially immersed in the coolant 49. The coolant 49 is supplied through a first through-opening 59 in the housing 9, which is opposite a first axial end of the stator 11, and discharged from the housing 9 through a second through-opening 61, which is located opposite the other axial end of the stator 11. The coolant movement is driven by a coolant pump. The coolant flows axially from the first through-opening 59 to the second through-opening 61 through the stator 11.

[0031] Another embodiment is in Fig. Figure 8e shows structures 63 arranged on the end faces of the rotor 5, which are designed, for example, as blades. These structures 63 generate a cooling airflow 65 during the rotation of the rotor 5, which cools the end ring 43 and the winding heads 15. Reference symbol list 1 electric machine 3 Rotor shaft 5 Rotor 7 rotor bearings 9 cases 11 Stator 13 Stator winding 15 winding heads 17 Closure structure 19 Statorjoch 21 Stator tooth 23 Stator slot 25 first ring-shaped component of the closure structure 27 Stator foot 29 second ring-shaped component of the closure structure 31 wedge-shaped projection 33 Wave winding 35 recording 37 Press element 39 Insulation paper 41 Impregnating agents 43 End ring 45 Half of the closure structure 47 Half of the closure structure 49 Coolant 51 radial channel of the rotor shaft 53 additional amount of coolant 55 Coolant supply line 57 Coolant supply opening 59 Passage opening 61 Passage opening 63 Rotor structure 65 Cooling airflow AL active length QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 211 317 A1

[0002]

Claims

[1] Stator for an electrical machine, in particular for an electric drive motor of an electric or hybrid vehicle, comprising a number of stator teeth (21) projecting from a stator yoke (19), wherein between each two stator teeth (21) a stator groove (23) is formed, into which a stator winding (13) is inserted, characterized by in that the free ends of the stator teeth (21) are designed free of projections in the direction of the stator slot and the stator slots (23) are covered by a separate closure structure (17) which consists of a first component (25) with good heat conduction, which has two tangential projections designed as tooth roots (27) projecting into the stator slot per stator slot (23), and a second component (29) with good heat conduction and poor electrical conduction, which closes a distance between the respective tooth roots (27) lying opposite one another in each stator slot (23). [2] Stator according to claim 1, characterized by that the second component (29) of the separate closure structure (17) with good thermal conductivity and poor electrical conductivity engages in a wedge-shaped manner in the distance between the opposite tooth roots (27) of the first component (25) with good thermal conductivity. [3] Stator according to claim 1 or 2, characterized by that the separate closure structure (17) is connected to at least one stator tooth (21) in a form-fitting and / or force-fitting and / or material-fitting manner. [4] Stator according to claim 1, 2 or 3, characterized by that the separate closure structure (17) projects beyond the active length (AL) of the electrical machine (1) on both sides to participate in an active cooling of the electrical machine (1). [5] Stator according to at least one of the preceding claims, characterized by that the separate closure structure (17) is ring-shaped. [6] Stator according to claim 5, characterized bythat the annular closure structure (17) is designed in one or two parts for axial insertion into the stator (11) on one or both sides. [7] Stator according to at least one of the preceding claims, characterized by that each stator winding (13) inserted in a stator slot (23) is at least partially surrounded by an insulating paper (39). [8] Stator according to claim 7, characterized by that the area of ​​the stator winding (13) opposite the second component (29) of the closure structure (17) with good thermal conductivity and poor electrical conductivity is free of insulating paper (39). [9] Stator according to at least one of the preceding claims, characterized by that in each stator slot (23) the free spaces between the stator winding (13) and the stator teeth (21) as well as the closure structure (17) are filled with an impregnating agent (41). [10] Stator according to at least one of the preceding claims, characterized bythat a wave winding (33) is inserted into the stator slot (23) as the stator winding (13).

Images